Atom – the smallest unit of matter “indivisible” Helium atom.

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Atom – the smallest unit of matter “indivisible” Helium atom

Electrons are placed in shells according to rules: 1)The 1st shell can hold up to two electrons, and each shell thereafter can hold up to 8 electrons.

Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons C would like to N would like to O would like to Gain 4 electrons Gain 3 electrons Gain 2 electrons

Learning Check A. X would be the electron dot formula for 1) Na2) K3) Al B. X would be the electron dot formula 1) B2) N3) P

IONIC BOND bond formed between two ions by the transfer of electrons

Formation of Ions from Metals Ionic compounds result when metals react with nonmetals Metals lose electrons to match the number of valence electrons Positive ions form when the number of electrons are less than the number of protons Group 1 metals  ion 1+ Group 2 metals  ion 2+ Group 13 metals  ion 3+

Formation of Sodium Ion Sodium atom Sodium ion Na  – e   Na + 2-8-1 2-8 11 p + 11 p + 11 e - 10 e - 0 1 +

Formation of Magnesium Ion Magnesium atom Magnesium ion  Mg  – 2e   Mg 2+ 2-8-2 2-8 (=Ne) 12 p + 12 p + 12 e- 10 e - 0 2 +

Learning Check A. Number of valence electrons in aluminum 1) 1 e - 2) 2 e - 3) 3 e - B. Change in electrons for octet 1) lose 3e - 2) gain 3 e - 3) gain 5 e - C.Ionic charge of aluminum 1) 3- 2) 5- 3) 3 +

Solution A. Number of valence electrons in aluminum 3) 3 e - B. Change in electrons for octet 1) lose 3e - C.Ionic charge of aluminum 3) 3 +

Learning Check Give the ionic charge for each of the following: A. 12 p + and 10 e - 1) 02) 2+3) 2- B. 50p + and 46 e- 1) 2+2) 4+3) 4- C. 15 p + and 18e- 2) 3+ 2) 3-3) 5-

Ions from Nonmetal Ions In ionic compounds, nonmetals in 15, 16, and 17 gain electrons from metals Nonmetal add electrons to achieve the octet arrangement Nonmetal ionic charge: Group 15  -3 Group 16  -2 Group 17  -1

Fluoride Ion unpaired electronoctet     1 - : F  + e  : F :     2-7 2-8 (= Ne) 9 p+ 9 p + 9 e- 10 e- 0 1 - ionic charge

Ionic Bond Between atoms of metals and nonmetals with very different electronegativity Bond formed by transfer of electrons Produce charged ions all states. Conductors and have high melting point. Examples: NaCl, CaCl 2, K 2 O

Ionic Bonds: One Big Greedy Thief Dog!

1). Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

IONIC COMPOUND NAMING Compounds that contain ions. Written using chemical formulas Rules are:

STEP 1 STATE THE CATION FIRST (THE NAME OF THE FIRST ELEMENT) METALS STEP 2 DROP THE ENDING OF THE NAME OF THE ANION (THE SECOND ELEMENT LISTED) AND ADD “IDE NON-METALS

Writing Ions One Na + (sodium ion)(METAL) and one Cl - (chloride ion)(Non-metal) bond to make NaCl (sodium chloride) One Mg 2+ (magnesium ion) and two F (fluoride ions) bond to make MgF 2 (magnesium fluoride) The number at the top is the oxidation number. Once they combine you have a subscript that tells how many of each type of atom are present. Mg 3 N 2

COVALENT BOND bond formed by the sharing of electrons

Covalent Bond Between nonmetallic elements of similar electronegativity. Formed by sharing electron pairs Stable non-ionizing particles, they are not conductors at any state Examples; O 2, CO 2, C 2 H 6, H 2 O, SiC

when electrons are shared equally NONPOLAR COVALENT BONDS H 2 or Cl 2

2. Covalent bonds- Two atoms share one or more pairs of outer-shell electrons. Oxygen Atom Oxygen Molecule (O 2 ) Oxygen Molecule (O 2 )

when electrons are shared but shared unequally POLAR COVALENT BONDS H2OH2O

Polar Covalent Bonds: Unevenly matched, but willing to share.

- water is a polar molecule because oxygen is more electronegative than hydrogen, and therefore electrons are pulled closer to oxygen.

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